Consider your odds of becoming a victim of phone theft: Last year, 3.1 million Americans had their phones stolen, according to a Consumer Reports survey. That's double the number from 2012.

Cellphone carriers haven't done enough to stop this growing epidemic, fueled by high smartphone resale values and a liquid secondhand market. Until they do, it's up to you to to protect your phone and aid police if it is stolen.

Starting Wednesday, the mobile security firm Lookout is adding a new tool for tracking down bad guys: the "theftie," a covert snapshot of someone trying to steal your phone.

If your phone is missing, technology might help you recover it. But it's important to act quickly and make sure to keep the police involved. Here are some tips from Geoffrey Fowler.

It's part of an app that alerts you to suspicious behaviors on your phone, like a screen password mistyped three times. You get an email containing your phone's location and a highly unflattering look at the person holding your phone—be they Samaritan or supervillain. Theft alerts cost $30 a year, bundled with Lookout's other services that block unsafe websites.

Lookout is part of a growing antitheft industry that makes use of the fact that the phone is already a powerful self-contained tracking device. To test the best options, free and paid, I challenged colleagues to grab and attempt to reset my phone. These services all protected my phone's data and provided useful clues in my hunt, though sometimes the trail went cold.

That's not to say we should become stolen-phone vigilantes—in fact, that's a terrible idea. "There are too many risks, aside from the location being wrong," says
Nuria Vanegas,
a public information officer with the Los Angeles Police Department. "You could knock on a door and it could be a grandma or it could be a gangster."

Lookout's app only triggers covert photos in specific circumstances. Still, does taking a surreptitious photo of anybody violate their privacy? Geoffrey Fowler asked Lookout co-founder and CTO Kevin Mahaffey about that very issue. Here's what he said.

Law-enforcement officials around the country tell me these services have limitations, but they'll take any help they can get. "We use it all the time and make arrests," says Sgt.
Danielle Newman,
a spokeswoman for the San Francisco Police Department.

Most recent smartphones come with access to free software that can report their location, remotely lock themselves and erase all their content. You can use these programs, like
Apple
's
free Find My iPhone, to track a phone thief in real time as he moves across town.

But you have to turn it on before your phone gets stolen. Apple asks for permission to activate Find My iPhone when you set up an iPhone. You can also turn it on later in the phone's iCloud settings.

In my tests, when a colleague pilfered my iPhone, I logged in to iCloud.com on a computer to find the phone's location, then set it to "lost mode," which locked the phone and displayed instructions on how to return it to me. Doing this also turned on an activation lock that would've made it hard for a crook to reset and resell the phone.

ICloud also gives you the option to remotely erase your phone or play an alarm on it, if you think it's near. (Annoyingly, the iCloud website doesn't open on Android phones. Does Apple think all our friends have iPhones?)

Apple's service usually allowed me to find my phone within a city block radius—but it became less useful when my colleague-thief took out the SIM card and turned off Wi-Fi. In those cases, or if the phone is turned off, Apple can only tell you when and where the phone last checked in (within 24 hours) and email you next time the phone is online.

Android phones offer similar services for free, but setting them up varies by maker. Recent Samsung phones can use the website FindMyMobile.Samsung.com, which worked well in my tests. Others can download
Google
's
Android Device Manager to find, alarm and remotely erase Android phones—but I had more difficulty getting it to find my phone.

ENLARGE

Carl Wiens

Another premium service, called Absolute
LoJack
,
comes embedded in the latest Samsung Galaxy phones and promises to track stolen phones, even if they're shipped overseas. The software, buried deep inside the phone, can reinstall itself and send data back to the company's servers. The $30-per-year service also comes with Absolute's own investigators, who read your phone's digital crumbs and coordinate recovery with police.

Lookout's app provides most of the same phone-finding services as the free apps, adding an extra set of virtual eyes over your phone. Right before your phone's battery runs out, Lookout will send you an email with its location. (Lookout calls that a signal flare.)

Lookout isn't the first app to take photos of thieves, but the company integrated it into a wider set of alerts. You get a theftie when Lookout spots any of the common steps criminals take when they steal a phone.

In my tests, I caught snaps of a colleague who snatched my phone and was able to track him to a block in downtown San Francisco. But it wasn't perfect: The location information wouldn't have been good enough for me to isolate him if he'd been a stranger. And Lookout's "scream" feature, which turns the phone into a police siren, wasn't loud enough for me to hear half a block away. (The company says scream was designed more to help people find phones lost in couches than to spook thieves.)

Lookout does more on Android phones, including firing off a theftie after an incorrect passcode. Its protections are more limited on an iPhone. Lookout can never take thefties, as Apple's privacy protections restrict remote access to the camera.

Another key question: Why shouldn't the industry provide better smartphone security?Lawmakers, cellphone makers and carriers are squabbling over the idea of a universal kill switch to turn stolen phones into bricks. Carriers, which profit from selling insurance policies and replacement phones, claim hackers could wreak havoc by exploiting a switch—a weak excuse for an industry with deep security expertise.

If you have an iPhone, just turn on Find My iPhone. If you have an Android phone and are worried about theft, $30 a year for Lookout's services would be well spent. A theftie alert was the first sign I had in some of my tests that my phone had been snatched.

Moreover, Lookout's real-time reports can help you make important decisions, like whether to wipe its data or call it while it is in someone's hands.

Then there's the real-life test: Earlier this month, a beta user of the Lookout software in Dyersburg, Tenn., had her phone stolen while shopping at
Wal-Mart
,
according to local police. When the suspected thieves mistyped her passcode, Lookout snapped thefties and sent them to her. She gave the photos to the police and posted them on
Facebook
.

A few days later, a friend of the victim identified the suspects by name. Police say after that the suspects turned themselves in and returned the phone.

Police making an arrest over a stolen phone??? That is total baloney. My son got his Iphone 5 ripped out of his hand in Atlanta and eventually tracked it down to a housing project. The cops told him that they would not pursue the thief there despite the fact that my son had offered to ID the guy.

The article states: In my tests, I caught snaps of a colleague who snatched my phone and was able to track him to a block in downtown San Francisco. But it wasn't perfect: The location information wouldn't have been good enough for me to isolate him if he'd been a stranger.

Yes it would have. Hang around that block and compare the "theftie" to the faces of people in that area.

The invention and adoption of Lojac systems have gone far to lower the rate of car theft in the nation (or at least make older model cars the preferred targets). Virtually all wireless products appear to be potentially able to be made "unstealable" if only the wireless providers were to cooperate. Lets hope companies like these prosper and spread; we may even reach a point where nobody in their right mind would even bother to steal them.

I'm not surprised the iCloud Web site doesn't work on an Android phone. It probably works poorly with Internet Explorer, too. We have to admit that - as much as we love our smart phones - some Web sites are going to be a lot easier to use with a desktop/laptop based browser.

The number of Web sites that still force me to try to use Internet Explorer make my head explode....

My wife's iPhone stolen at a restaurant. we re-activated her old iPhone, and after a few days noticed that some pictures of unfamiliar people showed up on it. We emailed those to the restaurant owner, who recognized one of the subjects...the busboy. He sent the cops around and after a little talking-to the phone was recovered. I don't understand how this happened, but it did.

@AARON ECKSTEIN@ROBERT WU If Apple made Windows Phones, they would be smug and say no one has managed to steal one so there is no need for an app to find them.

More seriously, I have a Windows Phone, and I neither of these apps are available. I do have the same ability to find a lost phone by logging into a webpage that they cited in the article.

There is a creepiness factor to covert "thefties" though. What if the phone wasn't stolen, but was being used to take pictures when the owner was elsewhere accessing the camera remotely - especially if the phone is left somewhere that folks shouldn't be snapping photos.

Like many other things, this Lookout App is a powerful tool, if it's used for good. If. Beware of the law of unintended consequences.

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